Ram upgrade

[KeithB5]

I want to upgrade my Ram and I am getting some conflicting information from different websites about how ram works.  One site says that if you have 4 ram slots then all 4 slots need the same sized ram with all the same specs from the same mfg in each slot for ram to work properly.  Another web site said the exact opposit.  That it really doesn't matter the size of ram in each slot as long as all the other specs are the same. 

Which one is right?

Here is what I have.  My motherboard is a 1pmmb-fm(formosa).  My cpu is intel core i7-3770.  In ram slot 1 and slot 3 I have two 8gb DDR3 ram purchased as a kit (which I recently installed).  in slot 2 (pre-installed) 4gb DDR3 ram that is mfg by Micron.  In slot 4 (pre-installed) I have a 8gb DDR3 ram mfg by samsung.

So based on what I have, does having mismatched Ram sizes with the same specs degrade my performance? 

[xuzo1]

Following, I also wonder about that question, HP makes the **bleep** things....let's see if they give us a straight answer...!

[banhien · Accepted solution]

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@KeithB5 wrote:

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Which one is right?

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So based on what I have, does having mismatched Ram sizes with the same specs degrade my performance? 

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@KeithB5

Both are right one way or the other BUT to be able to get full benefit of dual channel atchitecture uou need the first option. Running a micture of RAM may slow your machine a bit but unnoticable under normal conditions.

Regards.